U.S. President Barack Obama used the world's most popular social media website to deliver his economic message to the public Wednesday when he appeared in an online town hall that was streamed live from the California headquarters of Facebook.

Thousands of Facebook users had submitted questions to the president about his take on the huge U.S. deficit, the foreclosure crisis and other economic issues.

With jacket off, Obama acknowledged that the U.S. still faces "a whole series of challenges," including a sluggish housing market that he considers to be the biggest drag on the American economy.

He also warned that the U.S. economy could slip back into recession if spending is cut too sharply.

"If all we are doing is spending cuts, and we are not discriminating about it, if we are using a machete instead of a scalpel, and we are cutting out things that create jobs, then the deficit could actually get worse, because we could slip back into another recession," he said.

Obama maintained that his plan to cut $4 trillion from the deficit over the next 12 years is feasible through a mixture of spending cuts and higher taxes. The Republicans are proposing a bigger deficit cut through deeper spending cuts and overhauling Medicare and Medicaid.

Obama took selected online questions presented by Facebook founder Mark Zuckerberg and also answered several from members of a live studio audience.

The U.S. president was the first head of state to visit Facebook's Palo Alto, Cal., headquarters. The social media giant has more than 600 million users around the world. Obama is one of Facebook's most popular account users, with more than 19 million "likes."

Obama's 2008 election victory was due in part to his campaign's effective use of Facebook and similar social media sites to galvanize voters.

The U.S. president is on a three-day western swing through California and Nevada. He's scheduled to attend a series of fundraisers that will raise millions of dollars for his 2012 re-election campaign.